Disk detecting device and method

ABSTRACT

An optical disk reproducing apparatus having playback systems of CD and DVD containing their respective sync signals and method thereof. The playback systems respectively have sync detectors, and a controller analyzes a sync signal output from the sync detectors when a disk is detected to be mounted. The CD playback system is selectively driven when a CD sync signal is detected to perform a CD playback mode, and the DVD playback system is selectively driven when a DVD sync signal is detected to perform a DVD playback mode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk reproducing apparatus and methodand, more particularly, to a device and method of automaticallydetecting the kinds of disk mounted in an apparatus for reproducing aplurality of kinds of disks.

Generally, one representative type of optical disk performingnon-contact reading by using a laser beam is a compact disk(hereinafter, referred to as a CD). However, for the diskrecording/reproducing apparatus, higher speed, overwriting and higherdensity (larger capacity) are increasingly required. Meanwhile, for thedigital video compression technology, MPEG (Moving Picture ExpertsGroup) has become more practical in use. Accordingly, digital movingpicture disk media like a digital video disk (DVD) will emerge as thecore media of multimedia storage.

2. Description of the Related Art

FIG. 1 is a block diagram of a conventional DVD player. In this figure,disk 20 is a high-density optical disk, which can be DVD in this case.Pickup unit 111 is a shortwave optical head. It is assumed that thenumerical aperture be 0.6, and that the red semiconductor laserwavelength be used. Signal amplifier 112 amplifies a light signal outputfrom pickup unit 111 after converting it into an electrical signal.Demodulator/ECC decoder 113 demodulates the modulated signal output fromsignal amplifier 112, and corrects the error produced during playback.Servo controller 114 receives the output (focusing&tracking errorsignal) of signal amplifier 112 and the output (constant linear velocitycontrol signal) of demodulator/ECC decoder 113 in order to controlpickup unit 111. System decoder 116 decodes the DVD data stream outputfrom demodulator/ECC decoder 113, the stream being divided into a video(elementary) data stream and a audio (elementary) data stream. Videodecoder 117 decodes the video data stream output from system decoder 116so that it is converted into the form of reproducible video data.Encoder 118 encodes the video data output from video decoder 117 into acorresponding video displaying mode (NTSC or PAL), and then outputs themto a display. Audio decoder 119 converts the audio data stream encodedand output from system decoder 116 into the original data. D/A converter120 converts the data output from audio decoder 119 into an analog audiosignal. In FIG. 1 the system controller for controlling the overalloperation of the disk reproducing apparatus is not shown.

The DVD player constructed as above uses modulation, error correctionand a video encoding different from those of a general CD player so thattheir signal processings are completely different. The pit size andtrack pitch of a DVD and a CD are different, and their pickup unit 111laser wavelength and the numerical aperture of the objective lens aredifferent.

In the DVD recording/reproducing apparatus, it is important to reducethe size of a focusing spot for the purpose of higher density. For this,firstly, the laser wavelength becomes shorter, secondly, the objectivelens' numerical aperture becomes larger, and thirdly, a modulationhaving an excellent encoding efficiency is used. Here, for a DVD laserwavelength is 650-635 nm of a red semiconductor laser, the objectivelens' numerical aperture is 0.6, and EFM-plus (Eight to FourteenModulation plus) is used for modulation.

In order to reproduce information from the high-density optical disk,pickup unit 111 should be able to form a small focusing spot. Thediameter of the focusing spot is proportional to the wavelength λ oflight, and inversely proportional to the objective lens' numericalaperture, as shown in FIG. 2. At present, the lower limit of thesemiconductor laser wavelength is about 635 nm, as described above.Generally speaking, the DVD uses a laser wavelength of 650 nm as itsstandard, and the CD uses a laser wavelength of 780 nm. The DVD'snumerical aperture is 0.6, and the CD's is 0.45 so that the DVD'sdiameter of focusing spot becomes over about 60% of the CD's. Therefore,the DVD can obtain a playback signal equal to the CD's at about 2.6times the recording density of the CD. The DVD improves the waveform ofthe playback signal through the actual circuit processing so that it hasa recording density about 4.2 times the CD's.

FIG. 3 shows the relationship between pits and optical focus withrespect to a DVD and CD. FIG. 3 shows various dimensions of and arearatios between the DVD and the CD.

The characteristics of a DVD and a CD are shown in the following table1.

                  TABLE 1    ______________________________________                CD      DVD       REMARKS    ______________________________________    DISK DIAMETER  120 nm    120 nm   DVD is a both-                                      sided multi-    DISK THICKNESS                   1.2 nm    0.6 nm   layer.    RECORDING CAPACITY                   640 Mbyte                             4.7 Gbyte                                      In case of                                      single-sided                                      single layer    LASER WAVELENGTH                   780 nm    650 nm    OBJECTIVE'S   0.45       0.6    NUMERICAL    APERTURE    MINIMUM PIT SIZE                   0.9 μM                             0.4 μM    TRACK PITCH    1.6 μM                            0.74 μM    MODULATION MODE                  EFM       EFM-plus    ERROR CORRECTING                  CIRC      RS-PC    MODE    ______________________________________

In the table 1, the CD and DVD of the same disk diameter have manydifferences. However, their compatibility is very important because theCD format has an enormous amount of soft resources. The primaryimpedance in the compatibility between a DVD and a CD is to use aseparate optical pickup. In other words, in order to reproduceinformation on a disk, part of the optical system is formed according tothe thickness of disk. For this reason, the objective lens is designedin accordance with the thickness of disk. If the thickness of the diskdeviates from the value designed, spherical aberration is produced, andthe convergence of optical focus is decreased. More specifically, a DVDis 0.6 mm-thick, whereas a CD is 1.2 mm-thick so that the two kinds ofdisks cannot be reproduced with a single pickup unit. For theircompatibility, separate optical pickup units must be used.

In order to overcome such a problem, a double-focus optical unit wassuggested for both a CD and a DVD. In the optical pickup unit shown inFIG. 4, the optical focus for a DVD and the optical focus for a CD areformed spaced apart by a predetermined distance in the direction of anoptical axis. This solves the problem caused by the difference ofthickness of disk. The principle of the double-focus optical pickupshown in FIG. 4 is to overlap the operations of two kinds of lenses byusing a hologram. The numerical aperture of the objective lens of theoptical pickup is 0.6 in accordance with the standards of a DVD, and ahologram is provided to diffract part of its central light as if a lensrefracts it. The light not diffracted by the hologram is converged bythe objective lens whose numerical aperture is 0.6, to thereby form theoptical focus of a DVD. The diffracted light forms a hologram to besuitable for 0.4 numerical aperture of the hologram and objective lensand 1.2 mm-thick CD.

In case of the optical pickup shown in FIG. 4, the optical focus for aCD is formed farther than that for a DVD. Here, the photodetector isdisposed so that the reflection image of the optical focus converged onthe disk is formed thereon. If the DVD is reproduced, the optical focusof the DVD is converged on the disk, and the optical focus for the CDdeviates so that the image becomes unclear. The image of the opticalfocus for the DVD is formed on the photodetector but the reflectionlight at the optical focus for the CD is scattered widely to give noexternal impacts in DVD's playback. The reverse operation is performedin CD's playback.

In case of a system having a pickup capable of reproducing both DVD andCD or pickups capable of independently reproducing DVD and CD, it shouldbe operated in a corresponding mode by detecting the kind of diskinserted. The discrimination of DVD and CD can be implemented in variousways: to compare the sizes of the focus error detection signalsreproduced by the optical pickup; or to compare the sizes of RF signalsin accordance with the pit size.

However, the aforesaid method has the disadvantages that a long time isrequired to make a distinction between a CD and a DVD, and accuracy isdeteriorated.

SUMMARY OF THE INVENTION

In order to overcome such disadvantages of the prior art, it is anobject of the present invention to provide a device and method ofautomatically detecting the kinds of disks mounted in a system forreproducing multiple kinds of disks.

It is another object of the present invention to provide a device andmethod of detecting and analyzing the sync pattern of a mounted diskafter a CD mode is set initially in a system for reproducing a DVD and aCD, to thereby detect the kind of the disk mounted and alsoautomatically performing the corresponding disk reproducing modeaccording to the discrimination result.

It is still another object of the present invention to provide a deviceand method of detecting and analyzing the sync pattern of a mounted diskafter a DVD mode is set initially in a system for reproducing a DVD anda CD, to thereby detect the kind of the disk mounted and alsoautomatically performing the corresponding disk reproducing modeaccording to the discrimination result.

It is a further object of the present invention to provide a device andmethod of detecting and analyzing the sync pattern of a mounted disk ina disk reproducing system having CD and DVD sync detectors, to therebydetect the kind of the disk mounted and also automatically performingthe corresponding disk reproducing mode according to the discriminationresult.

To accomplish the above and other objects of the present invention,there is provided an optical disk reproducing apparatus having playbacksystems of CD and DVD containing their respective sync signals, the CDand DVD playback systems respectively having sync detectors, the systemsanalyzing a sync signal output from the sync detectors when a disk isdetected to be mounted, the CD playback system being selectively drivenwhen a CD sync signal is detected to perform a CD playback mode, the DVDplayback system being selectively driven when a DVD sync signal isdetected to perform a DVD playback mode.

In another aspect of the present invention, there is provided an opticaldisk reproducing apparatus having playback systems of CD and DVDcontaining their respective sync signals, the CD playback system havinga CD sync detector, the system analyzing whether a CD sync signal outputfrom the CD sync detector is detected or not when a disk is detected tobe mounted, the CD playback system being selectively driven when the CDsync signal is detected to perform a CD playback mode, the DVD playbacksystem being selectively driven when the CD sync signal is not detectedfor a predetermined time to perform a DVD playback mode.

In still another aspect of the present invention, there is provided anoptical disk reproducing apparatus having playback systems of CD and DVDcontaining their respective sync signals, the DVD playback system havinga DVD sync detector, the system analyzing whether a DVD sync signaloutput from the DVD sync detector is detected or not when a disk isdetected to be mounted, the DVD playback system being selectively drivenwhen the DVD sync signal is detected to perform a DVD playback mode, theCD playback system being selectively driven when the DVD sync signal isnot detected for a predetermined time to perform a CD playback mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a conventional digital video diskreproducing apparatus;

FIG. 2 is a diagram for explaining the relationship among the wavelengthof light, the numerical aperture of the objective lens, and the diameterof the optical focus in the digital reproducing apparatus;

FIG. 3 is a diagram explaining the relationship between pits and opticalfocus with respect to a video disk and a compact disk;

FIG. 4 is a diagram for explaining the principle of a conventionaldouble-focus optical pickup;

FIG. 5 is a block diagram of a device for detecting the kind of diskmounted in a disk player according to a first embodiment of the presentinvention;

FIGS. 6A-6E show the characteristics of detecting a CD frame sync signalin order to detect the kind of disk according to the first embodiment;

FIG. 7 is a block diagram of a device for detecting the CD frame syncsignal according to the first embodiment of the present invention;

FIG. 8 shows a flowchart for explaining the operation of detecting thekind of disk mounted in the disk player according to the firstembodiment;

FIG. 9 is a block diagram of a device for detecting the kind of diskmounted in a disk player according to a second embodiment of the presentinvention;

FIG. 10 is a diagram for showing an example of a DVD sync patternaccording to the second embodiment of the present invention;

FIGS. 11A-11C show the characteristics of detecting a DVD frame syncsignal in order to detect the kind of disk according to the secondembodiment;

FIG. 12 shows a flowchart for explaining the operation of detecting thekind of disk mounted in the disk player according to the secondembodiment.

FIG. 13 is a block diagram of a device for detecting the kind of diskmounted in a disk player according to a third embodiment of the presentinvention;

FIGS. 14A and 14B show a flowchart for explaining the operation ofdetecting the kind of disk mounted in the disk player according to thethird embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 5 shows a configuration of a device for automatically detecting thekinds of disks mounted in the disk recording/reproducing system havingCD and DVD reproducing systems according to a first embodiment of thepresent invention. It is assumed that optical pickup 111 uses a CD/DVDoptical pickup unit. Radio frequency (RF) receiver 512 amplifies a weaklight signal reproduced from optical pickup 111. Here, the RF signaloutput from RF receiver 512 is a signal reproduced from the CD or DVD(disk 20).

First, in the DVD reproducing system, DVD equalizer 516 filters the DVDband of the RF signal received, and equalizes it. Here, the DVD bandbecomes a wide band containing the CD band. DVD signal processor(digital signal processor) 517 receives the DVD band of data streamoutput from DVD equalizer 516 to thereby demodulate the modulated dataand correct errors produced during the above procedure. DVD signalprocessor 517 corresponds to demodulator/ECC corrector 113 shown inFIG. 1. A/V decoder 518 splits the data output from DVD signal processor517 into video data and audio data, and signal processes them. A/Vdecoder 518 corresponds to system decoder 116, video decoder 117 andaudio decoder 119.

Secondly, in the CD reproducing system, CD equalizer 513 filters the CDband of the RF signal output from RF receiver 512, and equalizes it. CDsignal processor (digital signal processor) 514 demodulates themodulated data stream output from CD equalizer 513, and corrects errorsproduced during the above procedure. Audio signal processor 515 signalprocesses the data output from CD signal processor 514.

This first embodiment of the disk reproducing apparatus has CD and DVDreproducing systems. Optical pickup 111 is a unit capable of reproducingboth a CD and a DVD. If a disk is mounted on the disk reproducingapparatus, it should be determined whether the disk mounted is a CD or aDVD, and then a corresponding reproducing system should be selectivelydriven. For this, CD sync detector 521 is incorporated in CD signalprocessor 514. Controller 511 decides the kind of the disk mounted andselectively drives a corresponding reproducing system, depending uponwhether the CD frame sync pattern output from CD sync detector 521 isdetected or not.

For the frame sync pattern of a CD a pattern not produced from themodulated data is used. This ensures reliable synchronization unless biterrors are produced. The data recorded on a CD uses EFM modulation.According to the EFM modulation, eight bits of data are converted into14 bits, and pattern combination of minimum three bits 3T and a maximum11 bits 11T is enabled. For the CD frame sync pattern,"1000000000010000000000100_(B) " (11T+11T+2T) not used as data and shownin FIG. 6a is used. The CD sync pattern shown as 6a is recorded in theCD in the form shown in FIGS. 6b or 6c.

The format of data recorded on the CD is made as FIG. 6d. CD syncdetector 521 is formed as in FIG. 7. Referring to FIG. 7, a data streaminput is applied to input register 71 and shifted. Reference register 72stores the CD frame sync pattern shown in FIG. 6a. Comparator 73compares pieces of parallel output bit data of input register 71 andpieces of parallel output bit data of reference register 72, and outputsthe result signal of comparison in units of bit. Sync signal detector 74logically combines the bit data output from comparator 73, and generatesa signal for deciding whether the CD sync signal is detected or not.Here, sync signal detector 74 uses a gate circuit. In case that HIGHlogic signals are all output from comparator 73 in sync detection, syncsignal detector 74 uses an AND gate. If the CD frame format is formed asshown in FIG. 6d, CD sync detector 521 detects a CD sync signal in thesync pattern cycle shown in FIG. 6e. The sync signal is generated in thecycle of 13.3 ms. The signal output from CD sync detector 521 formed asin FIG. 7 is applied to controller 511.

Controller 511 sets the CD mode as its initial mode if the disk isdetected to be mounted. At a time point when the constant linearvelocity (CLV) servo of the CD mode is ON, the frame sync signal of thereproducing system is produced in the cycle of 13.3 ms. Morespecifically, in case that data and their sync pattern are recorded onthe CD as shown in FIG. 6d, the frame sync signal is detected in thecycle of 13.3 ms during playback, as mentioned above. The frame syncsignal is generated from all the disks of CD and DVD. Here, the CLVservo is applied at a reference of 11T of the RF signal.

When controller 511 sets the CD mode as the initial operation mode, theCD sync pattern can be detected normally in case the mounted disk is aCD. However, if the DVD is mounted while the CD mode is set, the framesync signal cannot be detected while the CLV servo is applied. In thisembodiment, after the CLV servo is applied when the disk is mountedwhile the initial driving mode is a CD mode, it is determined whetherthe sync signal reproduced is detected or not, so as to decide whetherthe current mode is CD or DVD. According to the result decided, the CDor DVD reproducing mode is selectively driven.

FIG. 8 shows the procedure of selectively driving a correspondingplayback mode by controller 511 detecting the kind of disk mounted. Asshown in this figure, it is determined in this embodiment whether the CDframe sync signal is detected or not, after the CD mode is set as theinitial playback mode when the disk is mounted. If the sync signal isdetected according to the result, it is determined that the CD ismounted so that the CD reproducing system is selectively driven. If thesync signal is not detected for a predetermined time, it is determinedthat the DVD disk is mounted so that the DVD reproducing system isselectively driven.

Referring to FIG. 8, controller 511 checks whether any disk is mounted.First of all, controller 511 checks the state of input portion 510 tothereby find out the OPEN/CLOSED of the tray. If the tray isOPEN/CLOSED, controller 511 detects it in steps 811 and 813, and thendecides that the disk is mounted. Thereafter, controller 511 controls aservo controller (not shown) in step 815 so as to perform the focusingof the optical pickup 111 focusing. Here, optical pickup 111 is a unitusable for both CD and DVD. Therefore, the servo controller drivesoptical pickup 111 as the CD pickup unit. Controller 511 raises orlowers the optical pickup 111's focusing in step 815, and checks in step817 whether focus locking is performed. Here, if focus locking is notperformed, controller 511 senses this situation in step 817, and decidesin step 819 that the disk is not mounted. This case indicates that thetray is OPEN/CLOSED by a user while the disk is not mounted.

If focus locking is performed in step 817, this state indicates that thedisk is mounted on the tray. In this case, controller 511 controls theservo controller through steps 821-825 so as to rotate the disk mountedand turn on the tracking servo and CLV servo. Here, the servo controllerdrives the spindle motor under the control of controller 511 to therebyrotate the disk. In addition, the tracking servo is performed so thatoptical pickup 111 accurately traces the tracks. If the tracking servois finished, the rotation speed of the disk is controlled bymanipulating the spindle motor in the CLV mode of the CD playback mode.This situation shows that the CLV mode of the CD playback mode is setduring disk mounting and the detection of CD frame sync signal isprepared.

If the CD CLV servo is ON, controller 511 receives the output of CD syncdetector 514 in step 827, and checks whether the CD frame sync signal isdetected or not. Here, CD sync detector 521 receives the data streamfiltered and equalized in the CD band, and the data stream input iscompared with the previously stored CD frame sync pattern. Here, the CDframe sync pattern stored in reference register 72 is a peculiar patternhaving a format different from the data recorded in the CD. CD syncdetector 521 compares the sync pattern with the data stream received sothat the pattern having the same value is output as the CD frame syncsignal.

If the disk mounted is CD, the sync signal output from CD sync detector521 is generated in the cycle of 13.3 ms, as shown in FIG. 6e.Controller 511 senses in step 827 that the CD frame sync signal isdetected. The sync signal is detected for a predetermined number oftimes through steps 829 and 831. The number of detections of the CDframe sync signal is set to be high enough to decide that the diskmounted is a CD. If the CD frame sync signal is detected as many timesas the predetermined number, controller 511 establishes optical pickup111 as being for a CD in step 833, and resets the CLV servo for CDplayback. Then, in step 835, DVD signal processor 517 and A/V decoder518 are controlled to thereby inactivate the DVD playback system, and CDsignal processor 514 and audio processor 515 are controlled to therebyactivate the CD playback system. By doing so, the CD playback mode isperformed.

However, if the CD frame sync signal is not detected in step 827,controller 511 checks in step 837 whether a predetermined time passes.This means that the detection of the CD frame sync signal is performedfor the predetermined time even when the disk mounted is a DVD.Controller 511 waits to detect the CD frame sync signal for thepredetermined time after the CD CLV servo is ON. If the sync signal isnot detected for this time, the disk mounted is decided to be a DVD. Thepredetermined time is a period in which several CD frame sync signalscan be detected. If the CD frame sync signal is not received for thepredetermined time, controller 511 senses this state in step 837, anddecides in step 839 that the disk mounted is a DVD. In step 841 opticalpickup 111 is set for a DVD, and the DVD CLV servo is ON. If the CLV islocked thereafter, controller 511 senses it in step 843, and in step 845CD signal processor 514 and audio processor 515 are OFF to stop theoperation of the CD playback system. The DVD signal processor 517 andA/V decoder 518 are activated to drive the DVD playback system andperform the DVD playback mode.

In the first embodiment described as above, the CD playback mode isfirst performed when the disk is mounted in a disk playback system forreproducing both the CD and DVD, to thereby check whether there is a CDframe sync signal of the disk. If the CD frame sync signal is detected,the disk mounted is detected to be a CD, and the CD playback system isactivated to perform the CD playback mode. If not, the disk mounted isdecided to be a DVD, and the DVD playback system is activated to performthe DVD playback mode.

FIG. 9 shows a configuration of automatically detecting the kinds ofdisks mounted in disk recording/reproducing system having CD and DVDreproducing systems according to a second embodiment of the presentinvention. It is assumed that optical pickup 111 uses a CD/DVD opticalpickup unit. Radio frequency (RF) receiver 512 amplifies a weak lightsignal reproduced from optical pickup 111. Here, the RF signal outputfrom RF receiver 512 is a signal reproduced from the CD or DVD.

First, in the CD reproducing system, CD equalizer 513 filters the CDband of the RF signal output from RF receiver 512, and equalizes it. CDsignal processor 514 demodulates the data stream modulated and outputfrom CD equalizer 513, and correct errors produced during the aboveprocedure. Audio processor 515 signal processes the data output from CDsignal processor 514.

Secondly in the DVD reproducing system, DVD equalizer 516 filters theDVD band of the RF signal received, and equalizes it. Here, the DVD bandbecomes a wide band containing the CD band. DVD signal processor 517receives the DVD band of data stream output from DVD equalizer 516 tothereby demodulate the modulated data, and correct errors producedduring the above procedure. DVD signal processor 517 corresponds todemodulator/ECC corrector 113 shown in FIG. 1. A/V decoder 518 splitsthe data output from DVD signal processor 517 into video data and audiodata, and signal processes them. A/V decoder 518 corresponds to systemdecoder 116, video decoder 117 and audio decoder 119.

This second embodiment of the disk reproducing apparatus has CD and DVDreproducing systems. Optical pickup 111 is a unit capable of reproducingboth a CD and a DVD. If a disk is mounted on the disk reproducingapparatus, it should be determined whether the disk mounted is a CD or aDVD, and then a corresponding reproducing system should be selectivelydriven. For this, DVD sync detector 522 is incorporated in DVD signalprocessor 517. Controller 511 decides the kind of the disk mounted andselectively drives a corresponding reproducing system, depending uponwhether the DVD frame sync pattern output from DVD sync detector 522 isdetected or not.

For the frame sync pattern of a DVD a pattern not produced from themodulated data is used. This ensures reliable synchronization unless biterrors are produced. The data recorded on a DVD uses EFM-plusmodulation. In the DVD playback system using the EFM-plus modulation,the pattern of genuine data is maximum 11T (100000000001_(B)).Therefore, the DVD sync pattern commonly uses a pattern not used in thegenuine data. In this case, such a pattern should surpass a minimum 12T.The DVD uses multiple sync patterns in combination in an appropriateway. Here, those sync patterns commonly have specific patterns not usingthe data pattern. It is assumed in this embodiment that the commonpattern used in the sync pattern is 14T. The common pattern is assumedto be located at the lower 14 bits of each of the sync patterns.

FIG. 10 shows an example in which the DVD's sync pattern and pieces ofdata are stored in one sector format. In FIG. 10, reference characters Sindicate the sync patterns, D1-D being genuine data. Referencecharacters al-a2 represent the length of a sync pattern, b1-b2 being thelength of data. Reference characters cl-c2 indicate the length of a syncframe. Reference character E represents the length of two sync frames.Here, the data length b is far longer than the sync pattern length a.Reference character F indicates the number of rows of two frame syncsforming the sector. It is therefore noted that the size of one DVDsector becomes

    F*E=(c.sub.1 +c.sub.2)*F={(a.sub.1 +b.sub.1)+(a.sub.2 +b.sub.2)}*F

The sector format recorded in the DVD becomes as shown in FIG. 10. Inthis format, the sync pattern is formed as shown in FIG. 11a. Here, thesync pattern is formed with bits a, and the lower bits of the syncpattern have 14T commonly. The lower 14 bits of multiple sync patternsused in the DVD have the same value. Their upper bits have differentvalues. As shown in FIGS. 11b and 11c of the data transfer time betweenthe DVD frame sync patterns becomes 1.2 ms.

DVD sync detector 522 for detecting the DVD frame sync patterns shown inFIGS. 10 and 11 can be implemented in the same configuration as CD syncdetector 521 shown in FIG. 7. In this case reference register 82 of DVDsync detector 522 stores pieces of lower 14 bit data having a commonvalue in the DVD frame patterns, as shown in FIG. 11a. Comparator 73compares pieces of parallel output playback data stream of inputregister 71 and the DVD frame sync pattern of reference register 72, andoutputs the result signal of comparison in units of bit. Sync signaldetector 74 logically combines the bit data output from comparator 73,and generates a signal for deciding whether the DVD sync signal isdetected or not.

If the DVD sector format is formed as in FIG. 10, DVD sync detector 522detects a DVD frame sync signal in the sync pattern cycle shown in FIG.11c. The DVD frame sync pattern is reproduced in the cycle of 1.2 ms.DVD sync detector 521 detects the DVD frame sync signal, and outputs itto controller 511. Controller 511 sets the DVD mode as its initial modeif the disk is detected to be mounted. When the constant linear velocity(CLV) servo of the DVD mode is ON, and if the disk mounted is a DVDwhere data and sync patterns are recorded as shown in FIG. 10,controller 511 receives the DVD frame sync signal in the cycle of 1.2ms.

When controller 511 sets the DVD mode as the initial operation mode, theDVD sync pattern can be detected normally in case that the disk is amounted DVD. However, if the CD is mounted while the DVD mode is set,the frame sync signal cannot be detected while the CLV servo is applied.In this embodiment, after the CLV servo is applied when the disk ismounted while the initial driving mode is a DVD mode, it is determinedwhether the sync signal reproduced is detected or not, so as to decidewhether the current mode is CD or DVD. According to the result decided,the CD or DVD reproducing mode is selectively driven.

FIG. 12 shows the procedure of selectively driving a correspondingplayback mode by controller 511 detecting the kind of disk mountedaccording to the second embodiment. As shown in this figure, it isdetermined in this second embodiment whether the DVD frame sync signalis detected or not, after the DVD mode is set as the initial playbackmode when the disk is mounted. If the sync signal is detected accordingto the result, it is determined that the DVD is mounted so that the DVDreproducing system is selectively driven. If the sync signal is notdetected for a predetermined time, it is determined that the CD disk ismounted so that the CD reproducing system is selectively driven.

Referring to FIG. 12, controller 511 checks whether any disk is mounted.First of all, controller 511 checks the state of input portion 510 tothereby find out the OPEN/CLOSED of the tray. If the tray isOPEN/CLOSED, controller 511 detects it in steps 1211 and 1213, and thendecides that the disk is mounted. Thereafter, controller 511 controls aservo controller (not shown) in step 1215 so as to perform the focusingof the optical pickup 111 focusing. Here, optical pickup 111 is a unitusable for both a CD and a DVD. Therefore, the servo controller drivesoptical pickup 111 as the CD pickup unit. Controller 511 raises orlowers the optical pickup 111's focusing in step 1215, and checks instep 1217 whether focus locking is performed. Here, if focus locking isnot performed, controller 511 senses this situation in step 1217, anddecides in step 1219 that the disk is not mounted. This case indicatesthat the tray is OPEN/CLOSED by a user while the disk is not mounted.

If focus locking is performed in step 1217, this state indicates thatthe disk is mounted on the tray. In this case controller 511 controlsthe servo controller through steps 1221-1225 so as to rotate the diskmounted and turn on the tracking servo and CLV servo. Here, the servocontroller drives the spindle motor under the control of controller 511to thereby rotate the disk. In addition, the tracking servo is performedso that optical pickup 111 accurately traces the tracks. If the trackingservo is finished, the rotation speed of disk is controlled bymanipulating the spindle motor in the CLV mode of the DVD playback mode.This situation shows that the CLV mode of the DVD playback mode is setduring disk mounting and the detection of a DVD frame sync signal isprepared.

If the DVD CLV servo is ON, controller 511 receives the output of DVDsync detector 522 in step 1227, and checks whether the DVD frame syncsignal is detected or not. Here, DVD sync detector 522 receives the datastream filtered and equalized in the DVD band, and the data stream inputis compared with the previously stored DVD frame sync pattern. Here, theDVD frame sync pattern commonly has the reference data stored inreference register 72, and is a peculiar pattern (14T) having a formatdifferent from the data recorded in the DVD. DVD sync detector 522compares the sync pattern with the data stream received so that thepattern having the same value is output as the DVD frame sync signal.

If the disk mounted is a DVD, the sync signal output from DVD syncdetector 522 is generated in the cycle of 1.2 ms, as in FIG. 11c.Controller 511 senses in step 1227 that the DVD frame sync signal isdetected. The sync signal is detected for a predetermined number oftimes through steps 1229 and 1231. The number of detections of the DVDframe sync signal is set to be high enough to decide that the diskmounted is a DVD. If the DVD frame sync signal is detected as many timesas the predetermined number, controller 511 establishes optical pickup111 as being for a DVD in step 1233, and resets the CLV servo for DVDplayback. Then, in step 1235, DVD signal processor 517 and A/V decoder518 are controlled to thereby activate the DVD playback system, and CDsignal processor 514 and audio processor 515 are controlled to therebyinactivate the CD playback system. By doing so, the DVD playback mode isperformed for example, herein, if the number of times the frame syncsignal is detected is set to three times, five by five, it can beconfidentially decided that the disk mounted is a DVD.

However, if the DVD frame sync signal is not detected in step 1227,controller 511 checks in step 1237 whether a predetermined time passes.This means that the detection of the DVD frame sync signal is performedfor the predetermined time even when the disk mounted is a CD.Controller 511 waits to detect the DVD frame sync signal for thepredetermined time after the DVD CLV servo is ON. If the sync signal isnot detected for this time, the disk mounted is decided to be a CD. Thepredetermined time is a period in which several DVD frame sync signalscan be detected. If the DVD frame sync signal is not received for thepredetermined time, controller 511 decides in step 1239 that the diskmounted is a CD. In step 1241 optical pickup 111 is set for a CD, andthe CD CLV servo is ON. If the CLV is locked thereafter, controller 511senses it in step 1243, and in step 1245, CD signal processor 514 andaudio processor 515 are ON to activate the operation of the CD playbacksystem. The DVD signal processor 517 and A/V decoder 518 are inactivatedfor drive of the DVD playback system, and the CD playback mode isperformed.

In the second embodiment described as above, the DVD playback mode isfirst performed when the disk is mounted in a disk playback system forreproducing both a CD and a DVD, to thereby check whether there is a DVDframe sync signal of the disk. If the DVD frame sync signal is detected,the mounted disk is detected to be a DVD, and the DVD playback system isactivated to perform the DVD playback mode. If not, the disk mounted isdecided to be CD, and the CD playback system is activated to perform theCD playback mode.

FIG.13 shows a configuration of automatically detecting the kinds ofdisks mounted in a disk recording/reproducing system having CD and DVDreproducing systems according to a third embodiment of the presentinvention. It is assumed that optical pickup 111 uses CD/DVD opticalpickup unit. Radio frequency (RF) receiver 512 amplifies a weak lightsignal reproduced from optical pickup 111. Here, the RF signal outputfrom RF receiver 512 is a signal reproduced from the CD or DVD.

First, in the CD reproducing system, CD equalizer 513 filters the CDband of the RF signal output from RF receiver 512, and equalizes it. CDsignal processor 514 demodulates the data stream modulated and outputfrom CD equalizer 513, and corrects errors produced during the aboveprocedure. Audio processor 515 signal processes the data output from CDsignal processor 514.

Secondly, in the DVD reproducing system, DVD equalizer 516 filters theDVD band of the RF signal received, and equalizes it. Here, the DVD bandbecomes a wide band containing the CD band. DVD signal processor 517receives the DVD band of data stream output from DVD equalizer 516 tothereby demodulate the modulated data, and correct errors producedduring the above procedure. DVD signal processor 517 corresponds todemodulator/ECC corrector 113 shown in FIG. 1. A/V decoder 518 splitsthe data output from DVD signal processor 517 into video data and audiodata, and signal processes them. A/V decoder 518 corresponds to systemdecoder 116, video decoder 117 and audio decoder 119.

This third embodiment of the disk reproducing apparatus has CD and DVDreproducing systems. Optical pickup 111 is a unit capable of reproducingboth a CD and a DVD. If a disk is mounted on the disk reproducingapparatus, it should be determined whether the disk mounted is a CD or aDVD, and then a corresponding reproducing system should be selectivelydriven. For this, CD sync detector 521 is built in CD signal processor514, and DVD sync detector 522 is incorporated in DVD signal processor517. Controller 511 decides the kind of the disk mounted and selectivelydrives a corresponding reproducing system, depending upon whether the CDor DVD frame sync pattern output from CD or DVD sync detector 521 or 522is detected or not.

As explained above, CD and DVD have different frame sync patterns. Forthis reason, the disk reproducing system having CD and DVD playbacksystems can detect the kind of disk by checking the frame sync patternrecorded on the disk. Here, the CD frame sync pattern's characteristicsare the same as those in the first embodiment of FIG. 6. The DVD framesync pattern's characteristics are the same as those in the secondembodiment of FIGS. 10 and 11a through 11c.

The CD sync detector 521 for detecting the CD frame sync pattern and theDVD sync detector 522 for detecting the DVD frame sync pattern can beconstructed as in FIG. 7 according to the first and second embodiments.Here, reference register 72 of CD sync detector 521 stores the CD framesync pattern as shown in FIG. 6a. Reference register 72 of DVD syncdetector 522 stores the DVD frame sync pattern as shown in of FIG. 11a.

If the mounted disk is sensed initially, controller 511 sets its initialdriving mode as CD or DVD mode. Here, if controller 511 sets the initialdriving mode as CD mode, the CD frame sync pattern can be detectednormally in case that the disk mounted is CD. However, if the DVD ismounted while the CD mode is set, the frame sync signal cannot bedetected while the CLV servo is applied. In this case, controller 511converts the initial operating mode into the DVD mode so that the DVDframe sync signal can be detected by DVD sync detector 522.

Reversely, if controller 511 sets the initial driving mode as DVD mode,the DVD frame sync pattern can be detected normally in case that thedisk mounted is a DVD. However, if the CD is mounted while the DVD modeis set, the frame sync signal cannot be detected while the CLV servo isapplied. In this case, controller 511 converts the initial operatingmode into the CD mode so that the CD frame sync signal can be detectedby CD sync detector 521.

In this third embodiment of the present invention, the initial operatingmode is set as a CD mode when the disk is mounted, and then it ischecked whether the CD frame sync pattern is detected or not. If thepattern is detected, the CD playback mode is performed continuously. Ifnot, then the current mode is converted into the DVD mode to detect theDVD frame sync pattern and then is performed continuously the DVDplayback mode.

FIGS. 14a and 14b show a flowchart of the procedure of selectivelydriving a corresponding playback mode by controller 511 detecting thekind of disk when the disk is mounted, according to the third embodimentof the present invention.

Referring to FIG. 13, controller 511 detects the CD frame sync signal inthe sequence of which are the same as corresponding steps 811-837 shownin FIG. 8, respectively, according to the first embodiment steps1411-1435 of FIG. 14a. When the CD frame sync signal is detected, the CDplayback system is selectively driven to perform the CD playback mode.First of all, if the disk is detected to be mounted, the CD playbackmode is set as the initial driving mode and the output of CD syncdetector 521 is analyzed. If the CD frame sync signal is detected, it isthen determined that the disk mounted is CD, and the CD playback mode isperformed.

If the CD frame sync signal is not received for a predetermined time inthe state in which the CD playback mode is set as the initial drivingmode, controller 511 senses it in step 1437 of FIG. 14a. Then, in step1439 of FIG. 14b, the current mode is converted into the DVD mode sothat optical pickup 111 is controlled to reproduce information recordedon the DVD. In step 1449, the focusing servo is turned on. Through steps1451-1465, the DVD frame sync signal is detected and the DVD playbackmode is performed, wherein these steps are the same as correspondingsteps 1223-1237 shown in FIG. 12, respectively, according to the secondembodiment.

In the third embodiment of the present invention, the CD playback modeis first performed to check whether the CD frame sync signal of the diskis detected or not, when the disk is mounted in the disk playback systemcapable of simultaneously reproducing a CD and a DVD. If the CD framesync signal is not detected, the DVD frame sync signal is detected.

In another aspect of the present invention, the DVD playback mode isfirst performed to check whether the DVD frame sync signal of the diskis detected or not. If the DVD frame sync signal is not detected, the CDframe sync signal can be detected. In this situation, if the DVD framesync signal is detected, the disk mounted is detected to be a DVD, andthe DVD playback system is activated to perform the DVD playback mode.Here, if the DVD frame sync signal is not detected for a predeterminedtime, the DVD driving mode is converted into the CD mode, and then theCD frame sync signal is detected. By doing so, the disk mounted isdetermined to be a CD, and the CD playback system is activated toperform the CD playback mode.

In the first, second and third embodiments of the present invention,there has been explained a single pickup capable of reproducing both aCD and a DVD. However, the present invention can be applied equally to adisk playback system having a CD-only pickup and a DVD-only pickupseparately. In this configuration, the data stream generated from theCD-only pickup is first analyzed when a disk is mounted, to therebycheck whether the CD frame sync signal is detected or not. Here, if theCD frame sync signal is detected, the CD playback mode is performed. Ifthe signal is not detected for a predetermined time, the DVD-only pickupis activated to select the DVD playback system and perform the DVDplayback mode.

As described above, the present invention is capable of automaticallydetecting the kind of disk inserted into an apparatus for reproducingmultiple disks. Especially, the sync signal of the disk mounted isdetected to decide the kind of disk so that the kind of disk can beaccurately detected. According to the result detected, a correspondingdisk playback mode is automatically performed.

Therefore, it should be understood that the present invention is notlimited to the particular embodiment disclosed herein as the best modecontemplated for carrying out the present invention, but rather that thepresent invention is not limited to the specific embodiments describedin this specification except as defined in the appended claims.

We claim:
 1. An optical disk reproducing apparatus having playbacksystems of CD and DVD containing respective sync signals, the opticaldisk reproducing apparatus comprising:a controller; and the CD playbacksystem including a CD sync detector; wherein the controller initiallysets the optimal disk reproducing apparatus to a CD playback mode, andthen analyzes whether the CD sync detector detects a CD sync signal whena disk is detected to be mounted, the controller selectively driving theCD playback system when the CD sync signal is detected to perform the CDplayback mode, and selectively driving the DVD playback system when theCD sync signal is not detected for a predetermined time to perform a DVDplayback mode.
 2. An optical disk reproducing apparatus having anoptical pickup for a CD and a DVD having different sync signals, andalso having CD and DVD playback systems, the optical disk reproducingapparatus comprising:a controller; and the CD playback system includinga CD sync detector; wherein the controller controls the optical pickupfor CD-only, initially sets the optical disk reproducing to a CDplayback mode, and then analyzes whether the CD sync detector detects aCD sync signal when a disk is detected to be mounted, the controllerselectively driving the CD playback system when the CD sync signal isdetected to perform the CD playback mode, and controlling the opticalpickup for DVD-only and selectively driving the DVD playback system whenthe CD sync signal is not detected for a predetermined time to perform aDVD playback mode.
 3. A method of reproducing an optical diskreproducing apparatus having an optical pickup for a CD and a DVD havingdifferent sync signals, and also having CD and DVD playback systems, theCD playback system having a CD sync detector, the method comprising thesteps of;controlling the optical pickup for CD-only; initially settingthe optical disk reproducing apparatus to a CD playback mode, and thenanalyzing whether the CD sync detector detects a CD sync signal when adisk is detected to be mounted; selectively driving the CD playbacksystem when the CD sync signal is detected to perform the CD playbackmode; and controlling the optical pickup for DVD-only and selectivelydriving the DVD playback system, when the CD sync signal is not detectedfor a predetermined time to perform a DVD playback mode.
 4. An opticaldisk reproducing apparatus having playback systems of CD and DVDcontaining respective sync signals, the optical disk reproducingapparatus comprising:a controller; and the DVD playback system includinga DVD sync detector; wherein the controller initially sets the opticaldisk reproducing apparatus to DVD playback mode, and then analyzeswhether the DVD sync detector detects a DVD sync signal when a disk isdetected to be mounted, the controller selectively driving the DVDplayback system when the DVD sync signal is detected to perform the DVDplayback mode, and selectively driving the CD playback system when theDVD sync signal is not detected for a predetermined time to perform a CDplayback mode.
 5. An optical disk reproducing apparatus having playbacksystems of CD and DVD containing respective sync signals, the opticaldisk reproducing apparatus comprising:a controller; and the CD and DVDplayback systems respectively including sync detectors; wherein thecontroller analyzes a sync signal output from the sync detectors when adisk is detected to be mounted, selectively drives the CD playbacksystem when a CD sync signal is detected to perform a CD playback mode,and selectively drives the DVD playback system when a DVD sync signal isdetected to perform a DVD playback mode.
 6. An optical disk reproducingapparatus having a double-focus optical pickup for CD and DVD havingdifferent sync signals, and also having CD and DVD playback systems, theoptical disk reproducing apparatus comprising:a controller; and the CDand DVD playback systems respectively including sync detectors; whereinthe controller controls the optical pickup for CD-only and analyzeswhether the CD sync detector detects a CD signal when a disk is detectedto be mounted, the controller selectively driving the CD playback systemwhen the CD sync signal is detected to perform a CD playback mode, andthe controller controlling the optical pickup for DVD-only and analyzeswhether the DVD sync detector detects a DVD sync signal when a disk isdetected to be mounted, the controller selectively driving the DVDplayback system when the DVD sync signal is detected to perform a DVDplayback mode, and the controller controlling the optical pickup forCD-only and selectively driving the CD playback system when the CD syncsignal is detected to perform a CD playback mode.
 7. An optical diskreproducing apparatus having a double-focus optical pickup for CD andDVD having different sync signals, and also having CD and DVD playbacksystems, the optical disk reproducing apparatus comprising:a controller;and the CD and DVD playback systems respectively including syncdetectors, wherein the controller controls the optical pickup forDVD-only and analyzes whether the DVD sync detector detects DVD syncsignal when a disk is detected to be mounted, the controller selectivelydriving the DVD playback system when the DVD sync signal is detected toperform a DVD playback mode, and the controller controlling the opticalpickup for CD-only and selectively driving the CD playback system whenthe CD sync signal is detected to perform a CD playback mode.
 8. Anoptical disk reproducing apparatus having a double-focus optical pickupfor CD and DVD having different sync signals, and also having CD and DVDplayback systems, the optical disk reproducing apparatus comprising:acontroller; and the CD and DVD playback systems respectively includingsync detectors; wherein the controller analyzes a sync signal outputfrom the sync detectors when a disk is detected to be mounted, thecontroller selectively driving the CD playback system when a CD syncsignal is detected to perform a CD playback mode, and selectivelydriving the DVD playback system when a DVD sync signal is detected toperform a DVD playback mode.
 9. An optical disk reproducing apparatushaving playback system of CD and DVD containing respective sync signals,to reproduce data from a disk mounted in the optical disk reproducingapparatus, the optical disk reproducing apparatus comprising:acontroller; and one of the CD and DVD playback systems including acorresponding sync detector; wherein the controller initially sets afirst playback mode corresponding to the one of the CD and DVD playbacksystems including the corresponding sync detector, and subsequentlyanalyzes whether the sync detector detects a corresponding one of thesync signals when the disk is mounted detected to be mounted, thecontroller selectively driving the one of the CD and DVD playbacksystems including the corresponding sync detector when the correspondingone of the sync signals is detected to perform the first playback mode,the controller selectively driving the other one of the CD and DVDplayback systems when the one sync signal is not detected for apredetermined time to perform a second playback mode.
 10. An opticaldisk reproducing apparatus as claimed in claim 9, wherein said syncdetector comprises:an input register to shift the data from the mounteddisk; a reference register to store a reference frame sync pattern; acomparator to compare bits of the shifted data with bits of thereference frame sync pattern, to generate comparison results; and a syncsignal detector to logically combine the comparison results to determinewhether the sync signal occurs in the data from the mounted disk.
 11. Anoptical disk reproducing apparatus as claimed in claim 9, furthercomprising:an optical pickup; wherein the controller raises or lowersthe optical pickup relative to the mounted disk to perform focus lockingprior to initially setting the first playback mode.
 12. An optical diskreproducing apparatus having playback system of CD and DVD containingrespective sync signals, to reproduce data from a disk mounted in theoptical disk reproducing apparatus, the optical disk reproducingapparatus comprising:a controller; and the CD and DVD playback systemsincluding respective sync detectors; wherein the controller initiallysets a first playback mode corresponding to the one of the CD and DVDplayback systems, and subsequently analyzes whether a first one of thesync detectors detects a first one of the sync signals when the disk ismounted detected to be mounted, the controller selectively driving theone of the CD and DVD playback systems including the first one of thesync detectors when the first one of the sync signals is detected toperform the first playback mode, the controller then analyzing whether asecond one of the sync detectors detects a second one of the syncsignals if the first one of the sync detectors does not detect the firstone of the sync signals, and selectively driving the other one of the CDand DVD playback systems when the second one of the sync signals isdetected to perform a second playback mode.
 13. An optical diskreproducing apparatus as claimed in claim 12, wherein each of said syncdetectors comprises:an input register to shift the data from the mounteddisk; a reference register to store a reference frame sync pattern; acomparator to compare bits of the shifted data with bits of thereference frame sync pattern, to generate comparison results; and a syncsignal detector to logically combine the comparison results to determinewhether the sync signal occurs in the data from the mounted disk.
 14. Anoptical disk reproducing apparatus as claimed in claim 12, furthercomprising:an optical pickup; wherein the controller raises or lowersthe optical pickup relative to the mounted disk to perform focus lockingprior to initially setting the first playback mode.